Astronomers discover new luminous high-redshift quasar

November 6, 2018 by Tomasz Nowakowski, Phys.org report
The final calibrated spectrum of DELS J003836.10–152723.6. Credit: Wang et al., 2018.

An international team of astronomers has detected a new luminous quasar at a redshift of 7.02. The newly found quasi-stellar object (QSO), designated DELS J003836.10–152723.6, is the most luminous quasar known at a redshift of over 7.0. The discovery is reported in a paper published October 29 on the arXiv pre-print repository.

Powered by the most , bright at high redshift are important for astronomers as they are perceived as the brightest beacons highlighting the chemical evolution of the universe most effectively. They are the most luminous and most distant, compact objects in the observable universe and their spectrum can be used, for instance, to estimate the mass of supermassive (SMBHs).

However, QSOs are extremely rare and difficult to find. So far, only two quasars with redshifts over 7.0 have been identified. This limits our understanding of SMBH growth mechanism and reionization history.

Now, a group of researchers led by Feige Wang of the University of California, Santa Barbara (UCSB) announced the finding of a new quasar with a redshift above 7.0. The new discovery is part of the team's ongoing search for distant quasars and was made using photometric data from the DESI Legacy Imaging Survey (DELS), Pan-STARRS1 (PS1) imaging survey, as well as Wide-field Infrared Survey Explorer (WISE) mid-infrared all-sky survey.

"In this letter, we report the discovery of a luminous quasar at z = 7.021, DELS J003836.10–152723.6 (hereafter J0038–1527)," the astronomers wrote in the paper.

The team found that DELS J003836.10–152723.6 has an absolute magnitude at rest-frame wavelength 1450 Å of –27.1 and a bolometric luminosity of about 56 trillion solar luminosities. These values make it the most luminous quasar with a redshift of over 7.0 known to date.

According to the paper, DELS J003836.10–152723.6 hosts a black hole with a mass of around 1.33 billion solar masses. This black hole is accreting at the Eddington limit, with an Eddington ratio of 1.25. The researchers added that in order to grow such a at a redshift or around 7.0, it is necessary to have either massive seed black hole, or episodes of super-Eddington accretion, or a very low radiation efficiency.

"The existence of such SMBHs at EoR [epoch of reionization] requires either massive seeds or episodes of super-Eddington accretion under a typical radiation efficiency of about 0.1. Otherwise, the radiation efficiency must be much lower than that for thin disk accretion," the paper reads.

Furthermore, the astronomers found that the Civ broad emission line of this quasar is blue-shifted by more than 3,000 km/s to the systemic . The study also revealed three extremely high velocity Civ broad absorption lines (BALs) with velocity from 0.08 to 0.14 times the speed of light and total balnicity index of more than 5,000 km/s, which is indicative of the presence of relativistic outflows in the quasar.

The authors of the paper concluded that the findings make DELS J003836.10–152723.6 the first quasar found at the epoch of reionization with such strong outflows. Hence, the newly detected quasar could be an excellent target for future deep X-ray and (sub) millimeter observations aimed at studying active galactic nuclei (AGN) feedback on the formation and growth of the most massive galaxies in the early universe.

Explore further: Two high-redshift quasars discovered using OGLE

More information: Feige Wang et al. The Discovery of A Luminous Broad Absorption Line Quasar at A Redshift of 7.02. arXiv:1810.11925 [astro-ph.GA]. arxiv.org/abs/1810.11925

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6 comments

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fourinfinities
5 / 5 (2) Nov 06, 2018
"The team found that J0038–1527 has...a bolometric luminosity of about 56 trillion solar luminosities."

Citations of beamed power need to be clarified. A 5mW laser can resemble a 500W search-light if you look strait at it. Is 56 tsl the total power output, a good portion of which just happens to be aimed at us? Or is that the "assumed" power output, assuming the quasar is radiating equally in all directions, like a star?
RNP
5 / 5 (4) Nov 06, 2018
@fourinfinities
"The team found that J0038–1527 has...a bolometric luminosity of about 56 trillion solar luminosities."

Citations of beamed power need to be clarified. A 5mW laser can resemble a 500W search-light if you look strait at it. Is 56 tsl the total power output, a good portion of which just happens to be aimed at us? Or is that the "assumed" power output, assuming the quasar is radiating equally in all directions, like a star?


You are absolutely right.

In fact, the number is based on the *observed* luminosity and is therefore profoundly affected by beaming effects. It is not supposed to represent the total luminosity of the object/galaxy concerned, simply the observed luminosity.
Buddyroe
not rated yet Nov 07, 2018
The almighty Cosmos just blows me away "literally"
wduckss
1 / 5 (1) Nov 07, 2018
Galaxy Z8 GND 5296, red sfift 7,5078 ± 0,0004, distance13,1, speed 291,622 ± 120. https://en.wikipe...GS-zs8-1

How do the authors explain the low speeds quasar DELS J003836.10-152723.6 of 0.08-0.14 times the speed of light?
jonesdave
5 / 5 (2) Nov 07, 2018
Galaxy Z8 GND 5296, red sfift 7,5078 ± 0,0004, distance13,1, speed 291,622 ± 120. https://en.wikipe...GS-zs8-1

How do the authors explain the low speeds quasar DELS J003836.10-152723.6 of 0.08-0.14 times the speed of light?


The velocity reported is that of the blue shifted outflows, not the redshift of the galaxy itself.
Anonym262722
not rated yet Nov 10, 2018
As an outsider to GR/QM based physics field ( I am a retiree from modern surveying sciences of advanced math and estimation theory in photogrammetry and geodesy), my final of repeated advices to the new generation of physicists is to open any book, paper or presentation of Suntola Dynamic Universe web site PFS. I have explained the DU solution of the present article contradictions caused by the flaws of GR/QM in simple freshman terms since fall 2014 in my past posts of phys.org, Nature and WSU Master Classes. GR based cosmology even fooled the 2011 and 2017 Nobel committees and today the reported work of astrophysics is repeating the same mistaken path.

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